A Study On The Surface Modification With PEG-based Polymer And Its Protein Resistance

The surface modification with polymer such as polymer hydrogel and polymerbrush has attracted much attention because its potential application in many fields,such as biomedical devices, microelectronic and printing. After immobilization withpolymer, the chemical and physical performance of the surface is effectively modified.As its high grafting density ratio, easy to process and excellent protein resistance,Self-assembled monolayers (SAM) has been widely researched, however, the limitedrobustness of the thiol-contained SAM has long been its bottleneck which hinder itsapplication and development. In this dissertation, we fabricated a series ofPOSS-based hybrid polymer brush on the gold surface and investigated theirperformance of protein resistance. To further research the application of PEGcontaining poly(ether amine) at surface modification, we combine the technologies ofphotolithography and SAM, developed a binary mocropattern of polymer hydrogeland polymer brush on the gold surface.To enhance the robustness of the thiol-contained SAM, a novel hybrid polymerbrush containing PEG chains and POSS unit is designed, which combine themulti-anchors, vander Walls interaction between the hydrophobic POSS and thesurface. To research the combination between the relationship between the structureof the polymer brush and its nonfouling performance, a series of hybrid polymerbrushes (PPS1-4) with different lengths and numbers of PEG chain were fabricatedthrough the chemisorption of PEG-POSS-SH on the gold surface. The proteinadsorption of these hybrid brushes were investigated by AFM, XPS and SPR. Theamount of protein adsorption decreased with the increasing lengths and numbers ofPEG chains. The mass of BSA adsorption to the PPS4brush surface is about3ng/cm~2. After immersion in BSA solution for two months, PPS4brush can keep its long-termrobustness in protein resistance, while the reference PEG-SH layer lost its nonfoulingperformance. These POSS-containing hybrid polymer brushes might present a novelalternative for modification of gold surface with the excellent protein resistance of thelong-term.To further combine the technologies of photolithography and SAM, we developeda binary micropattern of anthracene-containing hyperbranched poly(ether amine)(hPEA-AN) network and poly(ether amine)(PEA) brush on gold surface wasdeveloped and explored. First, a micropatterned hPEA-AN network array on goldsurface was fabricated by photolithography via photodimerization of anthracenemoieties, and a PEA brush was subsequently immobilized on the remaining free goldsurface areas by chemical adsorption of thiol groups. The patterned hPEA-ANnetwork exhibits selectivity with respect to the adsorption of hydrophilic dyes: Methylorange is strongly adsorbed, but rhodamine6G is not, as indicated by the fluorescenceresponse. The PEA brush domain exhibits excellent protein adsorption repellency,whereas the hPEA-AN network layer readily adsorbs protein. These characteristicsmake the binary hPEA-AN network and PEA brush array sensitive to different kindsof dyes and proteins, which open up pathways to potential applications asmicrosensors, biochips, and bioassays.